The present invention relates to method and apparatus for separating semiconductor chips in which semiconductor chips are separated from a sheet for fixing a semiconductor wafer with the aim of dicing the semiconductor wafer into units of semiconductor chips and individual semiconductor chips are picked up and moved to a different site so as to be stored thereat.
JP-A-6-295930 and JP-A-6-97214 are known as conventional techniques of dicing a semiconductor wafer stuck to an adhesive sheet into units of semiconductor chips and peeling off a diced semiconductor chip from the adhesive sheet to pick it up.
JP-A-6-295930 describes that sticking force applied to the semiconductor chip can be weakened by scraping the back of the adhesive sheet to which the semiconductor chip to be peeled off is stuck by means of a sliding pin and the semiconductor chip under the application of the weakened sticking force can be raised uniformly by lifting push-up pins, provided circumferentially of the sliding pin, together with the sliding pin, thereby ensuring that the semiconductor chip can be peeled off from the adhesive sheet.
JP-A-6-97214 describes that an adhesive sheet to which many pellets are stuck is fixedly held with the pellets facing downwards, a spherically formed lower end of a needle unit forms a press surface for the adhesive sheet, a needle having a sharp tip is pushed down from the needle unit to peel off a pellet from the adhesive sheet and the peeled-off pellet is sucked by the action of vacuum by means of an underlying collet.
Incidentally, JP-A-1-264236 is known as a conventional technique of dicing a semiconductor wafer stuck to an adhesive sheet into units of semiconductor chips.
JP-A-1-264236 describes a wafer break technique according to which an adhesive sheet is stuck to a frame ring, a semi-fully cut wafer is fixed by the adhesive sheet and semiconductor chips put together in the form of a wafer are cut off in units of chips by moving a roller swelled at central portion while pressing the roller against the back of the adhesive sheet.
An object of the present invention is to fabricate products of high quality by separating a group of semiconductor chips, which is diced into semiconductor chips while being stuck to an adhesive sheet, from the adhesive sheet without damaging the individual semiconductor chips.
Incidentally, a semiconductor chip packaged in a mobile product such as contactless IC card or portable telephone is required to be thin in order that the thickness of the product can be small and the packaging efficiency can be promoted.
When the thin semiconductor chip as above is carried on a circuit board forming the mobile product such as contactless IC card or portable telephone to fabricate the above product, it is necessary to package the thin semiconductor chip without causing the chip to be damaged.
In the aforementioned JP-A-6-295930, however, the semiconductor chip is peeled off from the adhesive sheet by raising the push-up pins, provided circumferentially of the sliding pin, together with the sliding pin so as to uniformly lift the semiconductor chip and hence, the surface area of the semiconductor chip through which the chip is separated from the adhesive sheet is smaller than the surface area of the semiconductor chip through which the chip sticks to the adhesive sheet. Therefore, in the case of a thin semiconductor chip, there is great possibility that the chip fails to be separated and is broken.
In the aforementioned JP-A-6-97214, by lowering the needle having a sharp tip, the pellet is peeled off from the adhesive sheet. Accordingly, there is also great possibility of a thin semiconductor chip being prevented from separating out and being broken.
Besides, the aforementioned JP-A-1-264236 is concerned with the wafer break technique for cutting off semiconductor chips put together in the form of a wafer in units of chips.
As discussed above, neither of the aforementioned prior arts considers that when a thin semiconductor wafer stuck to the adhesive sheet is diced into units of thin semiconductor chips, a group of diced and aligned thin semiconductor chips is managed to be separated from the adhesive sheet without damaging the individual semiconductor chips.
According to the present invention, to solve the above problems, a thin semiconductor wafer stuck to an adhesive sheet is diced into units of thin semiconductor chips. Subsequently, a group of diced and aligned thin semiconductor chips is taken out by separating the adhesive sheet by means of a sucker plate without damaging the individual semiconductor chips. Through this, the present invention offers a method for separating semiconductor chips which can afford to fabricate products of high quality and a separating apparatus for implementing the method.
Namely, in the present invention, a semiconductor wafer stuck to an adhesive sheet with its silicon mirror surface facing downwards is sucked as a whole through its circuit surface side to a sucker plate which can suck the whole of wafer. In order to separate the sheet from a frame for fixing the sheet while the sheet being sucked, the sheet is cut by a cutter edge so as to be separated from the frame. To separate the sheet from the wafer, the wafer top surface is guided by a guide plate having a tip angle of 15xc2x0 and by causing the sheet to profile the tip of the guide plate, the sheet is peeled off in a direction making an angle of 45xc2x0 to the dicing direction on the wafer. The separating method and apparatus feature the above point.
Further, according to the semiconductor chip separating method and apparatus of the present invention, after the wafer is separated from the sheet through the aforementioned separating method, individual semiconductor chips are picked up independently of each other and transferred to a different site by means of a chip pick-up collet.
Advantageously, according to the invention, even a thin semiconductor wafer having a thickness of, for example, about 0.05 to 0.18 mm and a semiconductor wafer having an ordinary thickness of 0.4 to 0.5 mm can be diced into units of semiconductor chips while being stuck to the adhesive sheet and a group of diced and aligned semiconductor chips can be separated from the adhesive sheet by means of the sucker plate without damaging the individual semiconductor chips to permit fabrication of a high-quality mobile product such as contactless IC card and portable telephone.